This application relates to an improved design for an electrophoresis gel cassette.
Gel electrophoresis is a powerful analytic tool, which is used routinely in the analysis of nucleic acid sequences. Such analyses are now shifting from the research environment to become a part of the battery of tests performed by diagnostic laboratories. With this shift has come a need for simplified and less expensive gel cassettes.
The basic gel cassette is formed from two parallel plates held apart by spacers to define a gel cavity. One edge of the front plate may be lower than the back plate, and this edge of the front plate may be beveled or otherwise contoured to facilitate loading. (see, for example, U.S. Pat. No. 5,993,628 and 5,627,022). Because the plates are generally made from glass (to minimize interference with fluorescent detection and/or gel polymerization that could occur if plastics were used, the formation of this beveled or contoured edge during manufacturing can be expensive and time-consuming. Furthermore, the edge is prone to breakage in shipment and subsequent handling. Defects in the edge, such as chips or ripples, or a rough surface at the beveled edge can be translated into defects in the gel. Thus, quality control on this edge is a significant element in the overall cost of the gel cassette.
In accordance with the present invention, an electrophoresis cassette is made from two substrates separated by spacers, and a one-piece molded plastic edge adapter. The edge adapter provides the contoured region to facilitate sample loading, and because it is made from molded plastic is easier to make. Furthermore, the edge adapter has vertically extending arms which define the sides of the loading region and which, when affixed to the back substrate, prevent leakage of buffer solution from the region surrounding the electrophoresis origin. In a preferred embodiment, a groove in the bottom edge of the edge adapter receives the top edge of the front substrate to further define the position of the edge adapter in relation to the substrate. In an alternative embodiment of the invention, vertical divider fins are formed on the contoured surface of the edge adapter. These divider fins define loading wells for the introduction of sample into the lanes of the electrophoresis gel.